1. Field of the Invention
The present invention relates to a backlight module and particularly to a backlight module including a light guide plate having a plurality of side surfaces for light incidence.
2. Description of the Related Art
Currently, due to the global trend of energy-saving and environmental protection, light emitting diode (LED) elements gradually replace cold cathode fluorescence lamps (CCFL) in illumination applications such that mercury free and energy-saving light sources are produced.
Backlight modules can be categorized into direct type and edge type. However, the thickness of each of the conventional direct-type backlight modules is relatively large. In addition, light emitting diode elements can be used together with a light guide plate to form an edge-type backlight module. Single-edge-type backlight modules are common in edge-type backlight modules. In a single-edge-type backlight module, a plurality of light emitting diode elements are disposed at a side surface of a light guide plate. The side surface of the light guide plate which is corresponding to the light emitting diodes is the light incident surface and a top surface of the light guide plate is the light emitting surface. When the single-edge-type backlight module operates, the light emitted from the light emitting diode elements passes through the light incident surface to enter into the light guide plate. After affected by the light guide plate, the light is emitted out from the top surface.
However, in the single-edge-type backlight module, because the light only enters into the light guide plate from one side surface, the light guide plate is very thin and the number of the light emitting diode elements is limited, thus the brightness of the light emitting surface of single-edge-type backlight module can not be efficiently improved. Therefore, there is a desire to provide an edge-type backlight module of which the brightness is relatively high.